Road Glide: fast idle with ‘fly by wire’ throttle

My 2011 Road Glide is my ‘baby’, and when something starts behaving a bit odd I generally notice it fairly quickly. Twice now, once last fall and again just this past week, my bike has suddenly started idling at over 2,200 RPM. The normal idle is about 1,200 RPM, and the high idle revs make the things I normally do like using engine braking a bit challenging. Interestingly, if I ‘force rolloff’ the throttle (i.e.: roll it ‘down’ below its neutral point) the idle will drop. And frustratingly, the problem seems to magically ‘fix’ itself after a while, which has meant getting the service folks to investigate it has been challenging.

I think I have found the cause, as well as a temporary (?) fix.

Unlike older bikes, the 2011 and later Harley touring models like the Road Glide use a fully electronic ‘fly by wire’ throttle. That means there is no cable to adjust, lubricate, or bind up, which would be the logical thing to look at if your bike had a normal throttle and was exhibiting the symptoms I describe.

The cause on a ‘fly by wire’ throttle Harley is mostly likely something called a ‘throttle position sensor’. The TPS can be reset by cycling the ignition switch off/on for ten seconds in each state four times: you can read some advice to this effect on the Harley forums. I tried the ‘four on-four off’ igniting switch fix just now after confirming my bike was still idling somewhere in the 2000’s, and sure enough it started up normally at 1,200 RPM again afterwards. This also explains why the problem ‘magically’ goes away as well: eventually, you will cycle the ignition enough times to cause the idle reset to occur ‘organically’.

I suspect, though, that this is a temporary fix, and that high idle will recur periodically until the underlying issue is resolved. The TPS itself may be starting to fail, which would be the root cause of the problem. I have noticed that both times it went into ‘fast idle’ mode it was after/during a long day of riding in fairly warm temperatures, which probably puts some extra strain on an aging part.

The part itself doesn’t look expensive (under $50) or hard to install, but I think I’ll have the dealer mechanic check it out.